Coupling Accretion and Ejection: A New Evolutionary Framework for Class II Disks

by Dr Shridharan Baskaran (DAA, TIFR)

Tuesday 10 Feb 2026, 16:00 → 17:00 Asia/Kolkata

AG-69 (https://tifr-res-in.zoom.us/j/95955859360?pwd=pxZIyRidIcel1lhPDayZAQPgoT1C2V.1 Meeting ID: 959 5585 9360 Passcode: 342583)

The dispersal of protoplanetary disks sets the ultimate deadline for planet formation. To understand this process, we must understand the engine driving it: the complex interplay between mass accretion onto the star and mass loss through winds and jets. In this talk, I present a unified view of these dynamical processes using atomic and molecular tracers with high-sensitivity spectroscopy from the JWST Mid-Infrared Instrument (MIRI). First, we establish a robust framework for measuring accretion rates in high-extinction environments using mid-infrared neutral hydrogen (HI) lines. We provide the community with robust empirical relations to estimate accretion rate from MIRI spectra. Building on this, I present a comprehensive inventory of outflow tracers that reveals a fundamental shift in our understanding of disk winds. Furthermore, by spatially resolving fine-structure and molecular emission, we propose a possible evolutionary sequence within Class II sources: resolved, wide-angled outflows are driven only by sources with accretion rates ~1 magnitude higher than those exhibiting unresolved emission. Crucially, our initial qualitative analysis demonstrates that molecular H2 winds, not collimated jets, are the dominant mechanism for mass removal in Class II disks, consistently exceeding jet outflow rates by an order of magnitude. This finding suggests that molecular winds play the primary role in clearing the inner disk material. I will conclude by briefly introducing our upcoming study on X-ray driven PAH dissociation, which will provide a complete picture of the high-energy processes shaping inner disk environments.